Using the "as" Keyword

Using the "as" Keyword

• IrishAnto

  The result of the expression is always 'false' since a value of type 'int' is never equal to 'null' of type 'int ' is the warning i get when doing the above code segment....

  if(_EndingVendorLegs.EndID == null)

  {

  _EndingVendorLegs.EndID = ((Tracking.BusinessObjects.StopOrderLegDetail)tempOrderManifest[this.tempOrderManifest.Count - 2]).StopID;

  }

  
  

  
  
  

• curiousss

  it should be:

  _EndingVendorLegs.EndID = _EndingVendorLegs.EndID as ((Tracking.BusinessObjects.StopOrderLegDetail)tempOrderManifest[this.tempOrderManifest.Count - 1]).StopID;

  but this still may not work. you are needing to use a Type (object/class) to try to make the object into that type, should it support it. Example:

   

  this.theTextBox = this.theTextBox as MyClass;

  it will also not throw an exception but return null if it could not make the object into the specified type

   

  
  
  

• k_Prasad

  hi,

  Divide the statement into two like:

  Assuming Tracking.BusinessObjects.StopOrderLegDetail is typeX, that

  TypeX Instance = tempOrderManifest[this.tempOrderManifest.Count - 1] as typeX;

  _EndingVendorLegs.EndID = instance.StopID;

  Hope it helps

  
  
  

• Dietz

  as operator is great feature but should be used basically for reference types. There are some situations when should not be used like:
  - you can't use as operator when casting value to value type.
  - you are not performing unboxing conversion

  First case is a reason why you can't use as operator to determine does EndID will receive value or will be null, because EndID is int type. That is why you always get false.
  
  The code will be something like:
  
  Tracking.BusinessObjects.StopOrderLegDetail detail = tempOrderManifest[this.tempOrderManifest.Count - 2] as Tracking.BusinessObjects.StopOrderLegDetail;
  if (detail != null)
  {
      _EndingVendorLegs.EndID = detail.StopID;
  }

  
  
  

• Shaun Logan

  Here:

  _EndingVendorLegs.EndID = (tempOrderManifest[this.tempOrderManifest.Count - 1]).StopID as Tracking.BusinessObjects.StopOrderLegDetail;

  if(_EndingVendorLegs.EndID == null) // Means Casting was invalid

  {

  //////

  }

  else

  {

  // Do you work here......

  }

  I hope this will help.

  Best Regards,

  Rizwan

  
  
  
• Using the "as" Keyword